Water analyzer comprising a pneumatically driven multi-chamber peristaltic pump

ABSTRACT

A water analysis device with a pneumatically actuated multi-chamber peristaltic pump includes a base plate comprising a plurality of proximally open pump chambers disposed on a proximal side of the base plate. A pump membrane disposed on the proximal side of the base plate is configured to close the pump chambers. A cover plate is disposed on the pump membrane comprising a respective pneumatic actuator channel in a region of each of the pump chambers. The pneumatic actuator channel is configured to connect to an overpressure source which actuates the pump membrane. A connection channel formed as a groove on a distal side of the base plate is disposed between two of the pump chambers. A separate groove cover is disposed on the distal side of the base plate in a region of the groove. The separate groove cover closes a distal opening side of the groove.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2010/054333, filed on Mar. 31, 2010 and which claims benefit to European Patent Application No. 09168536.2, filed on Aug. 25, 2009. The International Application was published in German on Mar. 3, 2011 as WO 2011/023420 A1 under PCT Article 21(2).

FIELD

The subject matter of the present invention refers to a water analysis device comprising a pneumatically operated multi-chamber peristaltic pump.

BACKGROUND

In a water analysis device, liquids such as, for example, a water sample, a liquid dialysate, a liquid analyte, a rinsing liquid etc., are conveyed by pumps. If the analysis device is of a microfluidic design, peristaltic pumps are the pump type of choice. These comprise a plurality, for example, three, pump chambers which are successively filled and emptied so as to cause a unidirectional peristaltic pumping operation.

A microfluidic multi-chamber peristaltic pump is described in U.S. Pat. No. 5,593,290 A which comprises three pump chambers that are formed on the proximal side of a base plate and are each closed with an elastic pump membrane. The adjacent pump chambers are interconnected by a connection channel formed in the base plate as a proximally open groove closed with an intermediate plate. In the region of the pump chambers, the intermediate plate has corresponding continuous openings. The proximal side of the intermediate plate is provided with the elastic pump membrane, on which a cover plate is fixed that comprises a pneumatic actuator channel for each pump chamber.

Manufacturing this peristaltic pump is extremely intricate since the base plate and the intermediate plate must be aligned with each other with a tolerance of less than 0.1 mm. In order to provide that the respective overall volumes of the three pump chambers are as identical as possible, the intermediate plate is formed by a thin film. It is technically challenging to provide the continuous openings in the thin film with any accuracy.

SUMMARY

An aspect of the present invention is to provide a water analysis device with a pneumatically operated multi-chamber peristaltic pump that is simpler to manufacture.

In an embodiment, the present invention provides a water analysis device with a pneumatically actuated multi-chamber peristaltic pump which includes a base plate comprising a plurality of proximally open pump chambers disposed on a proximal side of the base plate. A pump membrane configured to be liquid-tight and elastic is disposed on the proximal side of the base plate. The pump membrane is configured to close the proximally open pump chambers. A cover plate is disposed on the pump membrane. The cover plate comprises a respective pneumatic actuator channel in a region of each of the proximally open pump chambers. The pneumatic actuator channel is configured so as to be connected to an over-pressure source configured to actuate the pump membrane. A connection channel is disposed between two of the proximally open pump chambers. The connection channel is formed as a groove on a distal side of the base plate. A separate groove cover is disposed on the distal side of the base plate in a region of the groove. The separate groove cover is configured to close a distal opening side of the groove.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basis of embodiments and of the drawings in which:

FIG. 1 shows a schematic illustration of a water analysis device formed by a base module and an exchangeable cartridge module in which a pneumatically operated multi-chamber peristaltic pump is arranged; and

FIG. 2 shows a longitudinal section of the peristaltic pump in FIG. 1.

DETAILED DESCRIPTION

In the water analysis device of the present invention, the connection channel between two pump chambers is formed as a groove on the distal side of the base plate. In the region of the connection channel groove, a separate groove cover is provided on the distal side of the base plate, which closes the distal opening side of the connection channel groove. The groove is thus now provided on the side of the base plate averted from the pump chambers. The groove may be closed with a simple groove cover. An intermediate plate with recesses or openings is no longer needed. The groove cover may be a large-surface body, for example, which covers the entire distal side of the base plate. No exact positioning of the groove cover is required, whereby the assembly is much facilitated.

The pump chambers can be closed with a single pump membrane or with separate pump membranes.

In an embodiment of the present invention, the base plate can, for example, be an injection molded plastic part comprising all pump chambers and the connection channels in the form of grooves. Since the base plate has recesses only on the distal and the proximal sides of the base plate, remolding poses no problems.

In an embodiment of the present invention, the groove cover can, for example, be a flexible cover film. The cover film is of limited flexibility so that it can adapt to irregularities on the distal side of the base plate. Leaks caused by irregularities; which would otherwise almost be inevitable with a rigid groove cover, are thereby avoided. Using a flexible cover film for the groove cover allows neglecting a high planarity on the distal side of the bas plate.

In an embodiment of the present invention, the cover film can, for example, be transparent. The cover film is, for example, transparent to laser radiation used to weld the cover film to the base plate. The transparence of the cover film thus makes it possible to weld the cover film to the base plate by laser welding. This allows for a reliably fluid-tight fixing of the cover film by means of an automated and thus cost-efficient manufacturing process.

In an embodiment of the present invention, the base plate and the cover film can, for example, be made from the same plastic material so that they have the same melting temperature. This facilitates the welding of the cover film to the base plate by laser welding.

In an embodiment of the present invention, respective vertical channels can, for example, be provided between the connection channel of the distal side of the base plate and the pump chambers, which vertical channels are perpendicular to the connection channel and respectively connect the pump chambers to the connection channel. Since the vertical channels have the same demolding direction as the pump chambers on the proximal side and the connection channel groove on the distal side of the base plate, the base plate can readily be made by injection-molding a plastic material.

In an embodiment of the present invention, the peristaltic pump can, for example, be a microfluidic peristaltic pump, wherein the pumping volume of a pump chamber is smaller than 10 μl. Observing the allowable tolerances is technically challenging, for example, with a microfluidic peristaltic pump, so that, for example, with respect to microfluidic peristaltic pumps, the present invention will lead to particular simplifications in the manufacture of a water analysis device using such a peristaltic pump.

In an embodiment of the present invention, the water analysis device can, for example, be formed by a base module including all electric components and an exchangeable cartridge module comprising the entire fluidic system including the peristaltic pump. The cartridge module may be a one-way article that is replaced and discarded when depleted or damaged.

In a schematic general view, FIG. 1 illustrates a process water analysis device 10 used for a quasi-continuous quantitative determination of an analyte in water 11. In the present case, the water analysis device 10 is fully immersed into the water 11 to be analyzed, i.e., it is designed as a so-called immersion probe. The water analysis device 10 is modular and is formed by a base module 12 containing all electric components and an exchangeable cartridge module 14 comprising the entire fluidic system which, in the present instance, is of microfluidic design. The cartridge module 14 is used only once and is replaced and discarded when depleted or in the event of a defect.

The cartridge module 14 comprises a carrier liquid tank 16 connected to the pump inlet of a pneumatically operated multi-chamber peristaltic pump 18 via a liquid conduit. The pump outlet of the peristaltic pump 18 is connected to a dialysis element 20 via a liquid conduit, in which element the analyte migrates from the water 11 into the carrier liquid.

A liquid conduit connects the dialysis element 20 to a measurement section 22, with a reagent being introduced at some point along this liquid conduit, which reacts, for example, in a color changing manner with the analyte to be determined. The measurement section 22 is associated with an analysis device 24 on the side of the base module, which device may, for example, be designed as a photometer, and determines the extinction of the liquid in the measurement section 22. The liquid is thereafter pumped into a waste tank 28.

The part of the peristaltic pump 18 on the side of the cartridge module is formed by a pump system whose actuation system is arranged in the base module 12. The actuation system is formed by an overpressure accumulator 30 and a vacuum accumulator 32, a pneumatic pump (not illustrated) that is connected to the overpressure accumulator 30 and the vacuum accumulator 32 and generates the necessary overpressure and vacuum, respectively, and three electrically switched change-over valves 34 that connect either the overpressure accumulator 30 or the vacuum accumulator 32 to the associated pump membrane of the peristaltic pump 18.

The peristaltic pump 18 is shown in detail in FIG. 2. The peristaltic pump 18 comprises a plastic material base plate 40 which has its proximal side provided with three pump chambers 41, 42, 43 as spherical recesses having a proximal opening. On the proximal side 44 of the base plate 40, a liquid-tight and elastic pump membrane 46 is arranged that closes the openings of the three pump chambers 41, 42, 43. The pump membrane 46 is formed from a fluorinated or partly fluorinated elastomer, for example, a material known by the name Viton, and has a thickness of 0.1 to 0.4 mm. As an alternative, the pump chambers 41, 42, 43 could also be closed with a separate individual pump membrane. Such a membrane may be formed by a circular membrane with an annular bead at the edge.

Proximal of the pump membrane 46, a cover plate 48 is applied onto the pump membrane 46, wherein the cover plate 48 has three pneumatic actuator channels 51, 52, 53 which are approximately perpendicular to the base plane of the base plate 40, each being aligned with the respective pump chamber 41, 42, 43 and ending approximately in the center of the pump chamber openings.

From each pump chamber 41, 42, 43, two vertical channels 60-65 respectively extend transversely to the base plane of the base plate 40 to the distal side of the base plate 40. Each pump chamber 41-43 has a respective vertical inlet channel 60, 62, 64 and a respective vertical outlet channel 61, 63, 65. The vertical outlet channel 61 of the first pump chamber 41 is connected to the vertical inlet channel 62 of the second pump chamber 42 through a horizontal connection channel 71. The vertical outlet channel 63 of the second pump chamber 42 is connected to the vertical inlet channel 64 of the third pump chamber 42 through another horizontal connection channel 73. The two connection channels 71, 73 are each formed as a distally open groove 70, 72 on the distal side of the base plate 40. In the region of the connection channels 71, 73, the distal side of the base plate 40 is covered by a separate groove cover 80 which is formed by a flexible transparent cover film 80 and distally covers the two connection channel grooves 70, 72.

The base plate 40 and the cover film 80 are made from the same plastic material so that they have the same melting point, and they are welded together fluid-tightly by laser welding or ultrasound welding. Heat sealing or thermal bonding can alternatively be used.

The vertical inlet channel 60 in the first pump camber 41 forms the pump inlet and the vertical outlet channel 65 of the third pump chamber 43 forms the pump outlet.

By correspondingly switching the associated change-over valve 34, pneumatic overpressure can be applied onto the proximal rear side of the pump membrane 46 through the actuator channels 51, 52, 53 so that the contents of the respective pump chamber 41, 42, 43 is expelled. By changing over the change-over valve 34, vacuum can be applied from the vacuum accumulator 32 onto the proximal rear side of the pump membrane 46 so that the same is withdrawn into the initial position illustrated in FIG. 2, whereby the respective pump chamber 41, 42, 43 is filled.

By filling the first pump chamber 41 and by subsequently filling the second pump chamber 42 while the first pump chamber 41 is emptied at the same time, and by subsequently filling the third pump chamber 43 while the second pump chamber 42 is emptied at the same time, a peristaltic pumping of the liquid from the pump inlet to the pump outlet is realized.

The absolute pressure in the overpressure accumulator 30 is at approximately 2.0 bar, and the absolute pressure in the vacuum accumulator 32 is at approximately 0.5 bar.

The largest diameter of the pump chambers 41-43 is 1.0 to 5.0 mm, the vertical height is 0.1 to 2.0 mm, so that he pump chambers 41-43 have a volume of approximately 1.0 to 20 μl, respectively.

The present invention is not limited to embodiments described herein; reference should be had to the appended claims. 

1-8. (canceled)
 9. A water analysis device with a pneumatically actuated multi-chamber peristaltic pump, the water analysis device comprising: a base plate comprising a plurality of proximally open pump chambers disposed on a proximal side of the base plate; a pump membrane configured to be liquid-tight and elastic disposed on the proximal side of the base plate, the pump membrane being configured to close the proximally open pump chambers; a cover plate disposed on the pump membrane, the cover plate comprising a respective pneumatic actuator channel in a region of each of the proximally open pump chambers, the pneumatic actuator channel being configured so as to be connected to an overpressure source configured to actuate the pump membrane, a connection channel disposed between two of the proximally open pump chambers, the connection channel being formed as a groove on a distal side of the base plate; and a separate groove cover disposed on the distal side of the base plate in a region of the groove, the separate groove cover being configured to close a distal opening side of the groove.
 10. The water analysis device as recited in claim 9, wherein the base plate is an injection-molded plastic part.
 11. The water analysis device as recited in claim 9, wherein the separate groove cover is a flexible cover film.
 12. The water analysis device as recited in claim 11, wherein the flexible cover film is transparent.
 13. The water analysis device as recited in claim 11, wherein the base plate and the flexible cover film are each made of a same plastic material and have a same melting temperature.
 14. The water analysis device as recited in claim 9, wherein a respective vertical channel is provided between the connection channel and the proximally open pump chambers, the vertical channels being disposed perpendicular to the connection channel.
 15. The water analysis device as recited in claim 9, wherein the pneumatically actuated multi-chamber peristaltic pump is a microfluidic peristaltic pump wherein a pumping volume of a pump chamber is smaller than 10 μl.
 16. The water analysis device as recited in claim 9, wherein the water analysis device further comprises a base module comprising all electric components and an exchangeable cartridge module comprising an entire fluidic system which comprises the pneumatically actuated multi-chamber peristaltic pump. 